The mechanism of white matter (WM) microstructure alteration in major depressive disorder (MDD) is unknown. Serum neurofilament (NF) levels have been identified as promising biomarkers for axonal damage and degeneration in neurological disorders. Furthermore, elevated plasma NF levels were also reported in depressive patients with treatment resistance. The current study investigated the serum NF levels of first-episode, medication-naïve patients with different severities of MDD and assessed their relationships with WM integrity. Diffusion tensor images and serum NF levels of 82 MDD patients and 72 age- and sex-matched healthy controls (HCs) were taken. We found that serum NF levels were significantly higher in patients with MDD than those in HCs. Fractional anisotropy (FA) of six brain WM tracts (the body and genu of the corpus callosum, left superior and posterior corona radiata, and bilateral anterior corona radiata) in patients with MDD were lower than those in the HCs after family-wise error-correction for multiple comparisons. Negative correlations between serum NF levels in the severe group of MDD and the decreased FA of the left anterior corona radiata were found in MDD, which might contribute to an understanding of the pathophysiological mechanism of MDD.

重度抑郁症 (MDD) 中白质 (WM) 微结构改变的机制尚不清楚。血清神经丝 (NF) 水平已被确定为神经系统疾病中轴突损伤和退化的有希望的生物标志物。此外，在治疗抵抗的抑郁患者中也报告了血浆 NF 水平升高。目前的研究调查了具有不同 MDD 严重程度的首发未用药患者的血清 NF 水平，并评估了它们与 WM 完整性的关系。采集了 82 名 MDD 患者和 72 名年龄和性别匹配的健康对照 (HC) 的扩散张量图像和血清 NF 水平。我们发现 MDD 患者的血清 NF 水平显着高于 HC 患者。六个脑 WM 束（胼胝体的身体和膝部）的分数各向异性 (FA)，MDD 患者的左上、后放射冠和双侧前放射冠）在进行多重比较的家庭式误差校正后低于 HCs。MDD重度组血清NF水平与左前放射冠FA降低呈负相关，这可能有助于理解MDD的病理生理机制。